New Hippopotamid Finds in Eurotas Valley (Laconia, Greece)
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Scientific Annals, School of Geology, Aristotle University of Thessaloniki Thessaloniki Special volume 99 57-62 Proceedings of the XIX CBGA Congress, Thessaloniki, Greece 2010 NEW HIPPOPOTAMID FINDS IN EUROTAS VALLEY (LACONIA, GREECE) Athanassiou A. and Bouzas D. Hellenic Ministry of Culture, Department of Palaeoanthropology–Speleology, Ardittou 34B, 116 36 Athens, Greece. [email protected],[email protected] Abstract: A new locality tracked down in the Eurotas Valley (Laconia, Greece) yielded mammalian dental remains of a young individual referred to as Hippopotamus antiquus. The findings are of very large size compared to already known specimens from Greece and W. Europe. The new locality is bi- ochronologically dated at the Early–Middle Pleistocene. Keywords: Hippopotamus Laconia, Peloponnesus, Greece, Pleistocene 1. Introduction area of the Eurotas Valley: Georgalas (1941) de- scribes a proboscidean molar from Skoúra, SE of During a geological survey in Eurotas valley (La- Sparta, which he refers to the Pliocene species conia, Peloponnesus) in October 2006, a new Anancus arvernensis. Sidiropoulou (1972) refers mammal locality was discovered. The site, dubbed an equid maxillary fragment from Vrontamás, pre- ―Myrtiá‖ (MYP), is located in the area among the serving cheek teeth in both sides, to Equus cabal- small town of Vlachiótis and the villages of Myrtiá lus forma primitiva; however, its dental characters, and Peristéri, near the road that leads from Myrtiá as the short protocones and the narrow styles, indi- to the main road of Skála–Vlachiótis (Fig. 1). It is cate that the specimen belongs to a stenonid horse a small remnant of an old terrace of the river Euro- of Late Pliocene or Early Pleistocene age. In a ra- tas, which outcrops above the present floodplain, vine of the same region Symeonidis (1970) men- forming a low hill (highest altitude: 38 m). It con- tions the presence of a (proboscidean?) tusk frag- sists of gravels and loose conglomerates deposited ment. The broader area of Vrontamás has recently in a fluvial environment. Part of the gravels has yielded some new mammal remains (Skourtsos been quarried several years ago. pers. com. and personal field data). Symeonidis & Theodorou (1986a) describe proboscidean skeletal and dental material from Vlachiótis, in the vicinity of Myrtiá, which they refer to Mammuthus meri- dionalis. Other Laconian localities, outside the Eu- rotas Valley, include the cave of Dyrós, which is particularly rich in Hippopotamus (Giannopoulos 2000; Symeonidis & Giannopoulos 2001), as well as the important anthropological sites of Apídima (Pitsios 1999; Tsoukala 1999) and Lakonís (Har- Fig. 1. Geographic location of the new fossil mammal vati et al. 2003). locality Myrtiá (MYP). Graphical scale in km. Contour interval: 100 m. 2. Systematics Order: Artiodactyla OWEN, 1848 The new locality yielded two Hippopotamus mo- Family: Hippopotamidae GRAY, 1821 lars that plausibly belong to the same individual, as Genus: Hippopotamus LINNAEUS, 1758 they were found in association and exhibit similar Hippopotamus antiquus DESMAREST, 1822 degree of wear. Material: MYP-1: upper left second molar (M2); Fossil mammal localities of Pliocene to Early MYP-2: upper left third molar (M3) (Fig. 2). The Pleistocene age are already known in the broader material is currently stored in the Museum of Pa- 57 laeontology and Geology of the National and Ka- the lingual and labial openings of the transverse podistrian University of Athens. valleys (the lingual one being more robust). In M3 the cingulum is preserved only mesially and distal- ly. The distal one is weaker than the corresponding structure of M2. The dimensions of M2 are (63.0) × (58.5) × 60.0 (mesiodistal diameter × labiolin- gual diameter × height, in mm), while those of M3 are (61.0) × (54.0) × 56.8 respectively (the dimen- sions in parentheses indicate inaccurate measure- ments, due to incomplete preservation). The degree of dental wear can provide information on the ontogenetic age of the Myrtiá individual. According to Laws (1968), who described the age groups of extant African hippos based on the erup- tion sequence of lower teeth, the first signs of wear on lower second molar appear at the age groups VII-VIII. The same author, based though on li- mited observations, states that the same criteria approximately apply on the upper teeth too. Thus the individual of Myrtiá can be aged into these Fig. 2. Hippotamus antiquus from Myrtiá. Left upper second molar (MYP-1): a, occlusal view; b, labial view. groups, which correspond to an ontogenetic age of Left upper third molar (MYP-2): c, occlusal view; d, la- 11±2 to 15±2 years in the extant populations bial view. Mesial side is on the left. Graphical scale in (Laws, 1968). cm. 3. Discussion Description: The two molars were found in ana- An exclusively African genus during the Holocene, tomical association; however no maxillary bone Hippopotamus was common in Europe during not even the roots are preserved. Both teeth are in most of the Pleistocene (especially in the western pristine condition: the enamel is wrinkled and only part), where it is present in hundreds of palaeonto- the mesial cusps (protocone and paracone) of M2 logical localities (Faure, 1981). The genus oc- show some signs of polishing due to very early curred in South, Central and Western Europe dur- enamel wear. The M3 must not have been erupted ing the Early and early Middle Pleistocene, but at the time of death. In occlusal view the teeth ex- subsequently retreated to the South (Iberian, Italian hibit the typical trefoil-shaped crown morphology, and Balkan peninsulas) till the end of the Middle which is characteristic for the Hippopotamidae. Pleistocene. In the Late Pleistocene the hippos The M2 has trapezoid shape, the mesial cusps be- were again widespread in Western Europe, reach- ing considerably wider than the distal ones. In M3 ing as far north as N. England. In general their the cusp pairs are placed rather oblique in relation biogeographic range extended north during the in- to the sagittal plane. All cusps are conical and con- terglacials and contracted to southern refugia dur- verge towards their apices. In labial or lingual view ing the glacials. The European population dimi- the mesial cusps appear almost straight, or bend nished and eventually became extinct during the slightly backwards, while the distal cusps are last glacial. clearly bent toward the centre of the crown. The mesial and distal cusp pairs are separated by very The earlier forms (Early to Middle Pleistocene), deep transverse valleys that open lingually and la- usually referred to as Hippopotamus antiquus, bially. The styles situated mesially and distally of were very large. Later forms (generally after the each cusp are very strong in M2, particularly the mid-Pleistocene) were smaller, comparable in size hypostyles. In M3 they are considerably weaker; to the recent African species H. amphibius and the distal metastyle is practically lacking, being usually referred to as such. A number of other spe- only visible near the base of the crown. Both mo- cies were also proposed, as H. incognitus FAURE, lars have a cingulum. In M2 it is very strong in all 1984 and H. tiberinus MAZZA, 1991, based on ana- sides of the tooth: mesially and distally it reaches tomical peculiarities of the skull or postcranial ske- the middle of the crown, while it forms a cuspid in leton, though they are not generally accepted with- 58 out reservation (Mazza 1995; Petronio 1995). Oth- er authors consider all European Pleistocene hip- popotamuses as belonging to the gradually evolv- ing extant species H. amphibius, in which they q recognize two subspecies (H. amphibius antiquus e w r and H. amphibius amphibius) (e.g. Kahlke, 1990; ty Kahlke, 2001). Since the taxonomy of the genus at u the species/subspecies level is still debated, the two species (antiquus–amphibius) taxonomic i scheme is provisionally accepted in the present 1@ study, following Petronio (1995). o 1# 1)1! 1$1^ Non-endemic Hippopotamus is already known 1% 2) from several sites in Greece (Fig. 3), but it is most- 1( 1& ly represented by few fragmentary finds in each 1* site. The richest sites are located in the Megalópo- lis Basin —sites Megalópolis (Melentis, 1966a) and Kyparíssia (personal data)—, as well as in Dyrós Cave (Petrochilos, 1958; Giannopoulos, Fig. 3. Distribution of non-endemic Hippopotamus- 2000; Symeonidis and Giannopoulos, 2001). The bearing localities in Greece: 1, Ravin Voulgárakis, presence of Hippopotamus sp. is also mentioned 2, Haliákmon Valley (unknown exact location), 3, Per- by Deprat (1904) at Panagia Heria, Euboea, to- díkkas, 4, Libákos, 5, Kapetánios, 6, Q-Profil, 7, Piniós gether with a Late Miocene assemblage, which Valley, 8, Toíchos, 9, Manzavináta, 10, Elis, 11, Ag. makes this determination rather doubtful. In a later Dimítrios, 12, Káto Salmeníko, 13, Limnón Cave, publication on the Miocene faunas of the island 14, Kyparíssia, 15, Megalópolis, 16, Marathoúsa, (Mitzopoulos, 1947) the genus is not included in 17, Apídima Caves, 18, Dirós Cave, 19, Myrtiá, the faunal lists. Endemic Hippopotamus (H. 20, Kos. Data according to Desio (1931), Psarianos (1954), Thenius (1955), Milójčić et al. (1965), Melentis creutzburgi BOEKSCHOTEN & SONDAAR, 1966) is (1966a, 1966b, 1969), Sickenberg (1976), Stratigopou- currently known from twenty localities in Crete los (1986), Symeonidis and Theodorou 1986b) Steen- (Lax, 1996; Iliopoulos et al., 2010), the most im- sma (1988), Koufos et al. (1989), Tsoukala (1999), portant of which is in the mountain basin of Ka- Symeonidis and Giannopoulos (2001), Reimann and tharó (Eastern Crete) (Boekschoten and Sondaar, Strauch (2008) and personal observations. 1966; Dermitzakis et al., 2005). as well as those from Dyrós, are much smaller than The Hippopotamus molars have only minimally Myrtiá, which is also consistent with their specific changed during the genus’ evolution and, conse- determination by the above authors as H.